Maybe it's all in my head, but the truck seems smoother at low RPM and idle now that I put in a new lift pump. The old one had a film of fuel on it all the time, but I couldn't find a leak. I replaced it with a Delphi unit from US Diesel Parts this morning, bled the low pressure system and fired it up. I noticed the smoother idle right away. I'm finding this confusing because I read on previous postings that when the lift pump on 1st gens dies, you notice a power loss at high rpm, but the truck runs ok at low speed. Did I just have an air leak that I've fixed while installing the new pump?

 

Did you take any pressure readings on the old pump to confirm that your pump was bad? Also, when I got my lift pump. Cummins gave me 2 gaskets. Did you put both of them in? Just wondering.

 

No, I didn't test pressure, I just took the film of fuel as a sign that something was wrong and changed the pump as a precaution. The priming lever worked and I wasn't making oil, so the pump probably made some pressure. The Delphi pump only had one gasket. I don't know why GM is making lift pumps for a 10 year old engine they don't use, but the price was right, $36 if I recall correctly.

 

Where did you find that lift pump? I would like to change mine for that price. :

 

I was wrong about the price, it's $32.51 here.

 

I just ordered one too. Mine is going on 13 years old. It's not seemingly giving any trouble but with the camper pulling season coming on, I don't want to get stranded because I didn't replace a $44 part. I'd feel pretty dumb about then
Plus, if I'm not getting enough pressure to the injector pump, it could damage it, couldn't it?

 

I just replaced my lift pump last weekend. Everything was running good, but I was installing new injectors, so I figured I'd replace the original lift pump.
I put in a Carter. $66 cost to my son's repair shop. One gasket. The old pump had been leaking a little oil thru the bottom of the gasket.
Truck does run smoother and idles about 50 rpm higher, but I think that's because of the new injectors, not the lift pump.
Jay

 

Seems strange but I noticed the same on my 93. My injector pump took a dump so i replaced it also from US Diesel. My fuel line was near impossible to loosen ,it actually started to spin the two halves of the lift pump comming apart. I used one gasket with some RTV and no problems.
Apache